（）is a high layer of cloud in the front of small flakes or cauhflower,white in colour with no dark shadows in between.

（）is a silvery cloud in the front of feathers or fibres...

单项选择题（）is a silvery cloud in the front of feathers or fibres seen high up against a blue sky.

（）are mainly caused by the gravitational pull of the mo...

单项选择题（）are mainly caused by the gravitational pull of the moon.

（）generally indicates that a gale or storm is approachi...

单项选择题（）generally indicates that a gale or storm is approaching.